Multi-nozzle gas-assisted electrospinning apparatuses

ABSTRACT

Provided herein are electrospinning systems, apparatuses, components, and processes for the preparation of nanofibers, including high throughput systems, apparatuses, and processes for producing high performance nanofibers.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.15/271,682, filed Sep. 21, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/458,023, filed Aug. 12, 2014, which is a USBypass continuation (CON) application under 35 USC 111(a) and claimsbenefit of International Patent Application No. PCT/US14/25699 filedMar. 13, 2014, which claims the benefit of U.S. Provisional ApplicationNo. 61/781,260 filed Mar. 14, 2013, each of which is incorporated hereinby reference in its entirety.

BACKGROUND OF THE INVENTION

A technique used to prepare fine polymer fibers is the method ofelectro-spinning. When an external electrostatic field is applied to aconducting fluid (e.g., a charged semi-dilute polymer solution or acharged polymer melt), a suspended conical droplet is formed, wherebythe surface tension of the droplet is in equilibrium with the electricfield. Electro-spinning occurs when the electrostatic field is strongenough to overcome the surface tension of the liquid. The liquid dropletthen becomes unstable and a tiny jet is ejected from the surface of thespinneret tip. As it reaches a grounded target, the jet stream can becollected as an interconnected web of fine sub-micron size fibers. Theresultant films from these nonwoven nanoscale fibers (nanofibers) havevery large surface area to volume ratios.

SUMMARY OF THE INVENTION

Provided herein is a nozzle or a multi-nozzle system (comprising aplurality of nozzles) for producing nanofibers. In some embodiments, thenozzle or multi-nozzle system allows for high throughput nanofiberprocessing. In certain embodiments, the nozzle or multi-nozzle systemalso provides for the preparation of high performance nanofibers—e.g.,nanofibers having uniform structures and components. In certainembodiments, such nanofibers allow for the production of nanofibers thathave narrow, uniform diameters. For example, in some instances, thestandard deviation of nanofibers provided, or prepared according tosystems and processes described, herein is less than 50% of the averagediameter.

Provided in certain embodiments herein are nozzles for producingnanofibers. Generally, such nozzles are suitable or configured for usein an electrospinning apparatus. In some embodiments, a nozzle providedherein comprises a first conduit and a second conduit, the first conduitpositioned inside the second conduit (e.g., as illustrated in thefigures). In specific embodiments, a nozzle (e.g., electrospinningnozzle) provided herein comprises:

-   -   a. a first conduit, the first conduit being enclosed along the        length of the conduit by a first wall having an interior and an        exterior surface (e.g., the interior surface facing the first        conduit and at least a portion of the exterior surface facing        the second conduit), and the first conduit having a first inlet        (or supply) end and a first outlet end; and    -   b. a second conduit, the second conduit being enclosed along the        length of the conduit by a second wall having an interior        surface, and the second conduit having a second inlet (or        supply) end and a second outlet end.

In some embodiments, the first conduit is positioned inside the secondconduit for a conduit overlap length (e.g., as illustrated by l¹ in thefigures). In certain embodiments, the conduit overlap length is anysuitable length, such as about 5 mm or more, or about 5 mm to about 100mm. In specific embodiments, the conduit overlap length is about 15 mmto about 100 mm. In more specific embodiments, the conduit overlaplength is about 20 mm to about 50 mm, e.g., about 30 mm. In someinstances, the first conduit is longer than the second conduit and inother instances, the second conduit is longer than the first conduit.And in yet other instances, both conduits are the same length. In someembodiments, the first outlet end extends beyond the second outlet endby a suitable amount (e.g., as illustrated by l² in the figures,described herein as the protrusion length—e.g., of the first conduit).In specific instances, the first outlet end extends beyond the secondoutlet end by about −0.5 mm to about 1.5 mm. In more specific instances,the first outlet end extends beyond the second outlet end by about 0 mmto about 0.8 mm. In still more specific embodiments, the first outletend extends beyond the second outlet end by about 0.1 mm to about 0.5mm.

In some embodiments, the first conduit has a first diameter (e.g.,diameter of the interior surface of the first walls) and the secondconduit has a second diameter (e.g., diameter of the interior surface ofthe second walls). Generally, given the configuration of the firstconduit inside the second conduit, the second diameter is larger thanthe first diameter. In some embodiments, the first diameter is anysuitable diameter. In specific embodiments, the first diameter is about0.05 mm to about 3 mm. In more specific embodiments, the first diameteris 0.3 to 3 mm, about 0.5 mm to about 1 mm, or about 0.6 mm to about 0.9mm. In some embodiments, the walls surrounding the first conduit have afirst wall diameter of about 0.1 to about 4 mm, e.g., about 0.5 mm toabout 3.8 mm. In more specific embodiments, the first wall diameter isabout 0.8 mm to about 1.8 mm, or about 1 mm to about 1.5 mm. In someembodiments, the second diameter is any suitable diameter. In specificembodiments, the second diameter is about 0.1 mm to about 5 mm. In morespecific embodiments, the second diameter is about 0.8 to 4 mm, about 1mm to about 2.5 mm, about 0.8 mm to 2 mm (such as when the third conduitinside which the second conduit is positioned is present), or about 1.3mm to 1.6 mm.

In various embodiments, the conduits described herein have any suitableshape. In some embodiments, the conduits are cylindrical (e.g., oval orcircular cylinders), prismatic (e.g., an octagonal prism), conical(e.g., a truncated cone), pyramidal (e.g., a truncated pyramid, such asa truncated octagonal pyramid), or the like. In specific embodiments,the conduits are cylindrical (e.g., wherein the conduits and wallsenclosing said conduits form needles). In certain embodiments, the wallsof a conduit are parallel, or within about 1 or 2 degrees of parallel(e.g., wherein the conduit forms a cylinder or prism). In otherembodiments, the walls of a conduit are not parallel (e.g., wherein thediameter is wider at the inlet end than the outlet end, such as when theconduit forms a cone (e.g., truncated cone) or pyramid (e.g., truncatedpyramid)). In certain embodiments, the walls of a conduit are withinabout 15 degrees of parallel, or within about 10 degrees of parallel. Inspecific embodiments, the walls of a conduit are within about 5 degreesof parallel (e.g., within about 3 degrees or 2 degrees of parallel). Insome instances, conical or pyramidal conduits are utilized. In suchembodiments, the diameters for conduits not having parallel walls referto the average width or diameter of said conduit. In certainembodiments, the angle of the cone or pyramid is about 15 degrees orless, or about 10 degrees or less. In specific embodiments, the angle ofthe cone or pyramid is about 5 degrees or less (e.g., about 3 degrees orless).

In some embodiments, the distance between the exterior surface of thefirst wall and the interior surface of the second wall (the conduit gapthereof) is any suitable distance. In some embodiments, the distance ison average less than 0.5 mm. In specific embodiments, the distancebetween the exterior surface of the first wall and the interior surfaceof the second wall is on average less than 0.3 mm. In more specificembodiments, the distance is on average about 0.01 mm to about 0.3 mm.In still more specific embodiments, the distance is on average about0.05 mm to about 0.3 mm.

In certain embodiments, provided herein is a nozzle component comprisinga ratio of the conduit overlap length (e.g., as illustrated byl¹)-to-second diameter (e.g., as illustrated by d²) of at least 5. Inspecific embodiments, the ratio is about 10 or more. In more specificembodiments, the ratio is about 13 or more. In still more specificembodiments, the ratio is about 15 or more, e.g., about 17 or more. Instill more specific embodiments, the ratio is about 18 or more, e.g.,about 19.

In some embodiments, provided herein is a nozzle component comprising aratio of the average distance between the exterior surface of the firstwall and the interior surface of the second wall (also described hereinas the conduit gap, and, e.g., illustrated in the figures by d⁴) to thesecond diameter (e.g., illustrated in the figures as d²) of less than0.25, e.g., about 0.2 or less. In specific embodiments, the ratio of theconduit gap-to-second diameter is less than 0.15. In more specificembodiments, the ratio is less than 0.1. In still more specificembodiments, the ratio is about 0.05 or less, e.g., about 0.04.

In some embodiments, provided herein is a nozzle component comprising aratio of the protrusion length of the first conduit (e.g., asillustrated by l2 in the figures)-to-second diameter (e.g., asillustrated by d2 in the figures) of less than 1. In specificembodiments, the ratio is less than 0.5. In more specific embodiments,the ratio is about 0.3 or less.

In some embodiments, provided herein is a multi-nozzle configurationcomprising a ratio of the distance between two adjacentnozzles-to-second diameter (e.g., as illustrated by d² in the figures)of about 0.5 to about 50. In some embodiments, the ratio is about 0.5 toabout 25, or about 0.5 to about 10, e.g., about 1 to about 5. Inspecific embodiments, the ratio is about 1. In other specificembodiments, the ratio is about 5.

In certain embodiments, a nozzle provided herein comprises a firstconduit that is fluidly connected (e.g., via the inlet or supply end) toa first supply chamber, the first supply chamber configured to provideliquid polymer (e.g., polymer melt or polymer solution) to the firstconduit. In some embodiments, a nozzle provided herein comprises asecond conduit that is fluidly connected (e.g., via the inlet or supplyend thereof) to a second supply chamber, the second supply chamberconfigured to provide pressurized (or high velocity) air to the secondconduit. In some embodiments, the second supply chamber is a pressurizedair tank, an air pump, a chamber containing a fan, or the like. Incertain embodiments, the first and second supply chambers are present ina manifold described in more detail herein. In certain embodiments, anozzle component described herein is configured to receive a voltage(e.g., sufficient to produce an electric field strong enough to overcomethe surface tension of a liquid polymer—e.g., a polymer solution orpolymer melt).

In specific embodiments, provided herein is a nozzle, or anelectrospinning apparatus comprising a nozzle, the nozzle comprising:

-   -   a. a first conduit, the first conduit being enclosed along the        length of the conduit by a first wall having an interior and an        exterior surface (e.g., the interior surface facing the first        conduit and at least a portion of the exterior surface facing        the second conduit), the first conduit having a first inlet (or        supply) end and a first outlet end, and the first conduit having        a first diameter (e.g., defined by the diameter of the interior        surface of the first walls); and    -   b. a second conduit, the second conduit being enclosed along the        length of the conduit by a second wall having an interior        surface, the second conduit having a second inlet (or supply)        end and a second outlet end, and the second conduit having a        second diameter (e.g., defined by the diameter of the interior        surface of the second walls);    -   the first and second conduit having a conduit overlap length,        wherein the first conduit is positioned inside the second        conduit, the exterior surface of the first wall and the interior        surface of the second wall being separated by a conduit gap, the        first outlet end protruding beyond the second outlet end by a        protrusion length, and wherein:        -   i. the ratio of the conduit overlap length-to-second            diameter is about 10 or more (e.g., about 13 or more, or            about 18 or more),        -   ii. the ratio of the average conduit gap-to-second diameter            about 0.2 or less (e.g., about 0.1 or less, or about 0.05 or            less), and/or        -   iii. the ratio of the protrusion length-to-second diameter            is about 0.3 or less.

In some embodiments, provided herein is a nozzle, or an electrospinningapparatus comprising a nozzle, the nozzle comprising:

-   -   a. an inner conduit, the inner conduit being enclosed along the        length of the conduit by an inner wall having an interior and an        exterior surface (e.g., the interior surface facing the inner        conduit and at least a portion of the exterior surface facing        the outer conduit), the inner conduit having an inner conduit        inlet (or supply) end and an inner conduit outlet end, and the        inner conduit having an inner conduit diameter (e.g., defined by        the average diameter of the interior surface of the inner        walls); and    -   b. an outer conduit, the outer conduit being enclosed along the        length of the conduit by an outer wall having an interior        surface, the outer conduit having an outer conduit inlet (or        supply) end and an outer conduit outlet end, and the outer        conduit having an outer conduit        -   diameter (e.g., defined by the average diameter of the            interior surface of the outer walls); the inner and outer            conduit having a conduit overlap length, wherein the inner            conduit is positioned inside the outer conduit (e.g., with            optional additional inner conduits positioned inside the            inner conduit), the exterior surface of the inner wall and            the interior surface of the outer wall being separated by a            conduit gap, the inner conduit outlet end protruding beyond            the outer conduit outlet end by a protrusion length, and            wherein:        -   i. the ratio of the conduit overlap length-to-outer conduit            diameter is about 10 or more (e.g., about 13 or more, or            about 18 or more),        -   ii. the ratio of the average conduit gap-to-outer conduit            diameter about 0.2 or less (e.g., about 0.1 or less, or            about 0.05 or less), and/or        -   iii. the ratio of the inner conduit protrusion            length-to-outer conduit diameter is about 0.3 or less.

In certain embodiments, an electrospinning apparatus (or nozzle)provided herein comprises a nozzle having a first (or inner) conduitthat is fluidly connected (e.g., via the inlet or supply end) to a firstsupply chamber, the first supply chamber configured to provide liquidpolymer (e.g., polymer melt or polymer solution) to the first conduit.In some embodiments, an electrospinning apparatus provided hereincomprises a nozzle having a second (or outer) conduit that is fluidlyconnected (e.g., via the inlet or supply end thereof) to a second supplychamber, the second supply chamber configured to provide pressurized (orhigh velocity) air to the second conduit. In some embodiments, thesecond supply chamber is a pressurized air tank, an air pump, a chambercontaining a fan, or the like. In certain embodiments, an apparatusprovided herein comprises a power source configured to provide a voltageto the nozzle component. In further embodiments, an apparatus providedherein comprises a grounded collector (e.g., for collecting nanofibersproduced by the electrospinning apparatus).

In specific embodiments, the ratio of the conduit overlaplength-to-outer conduit diameter is about 10 or more (e.g., about 13 ormore, or about 18 or more). In further or alternative specificembodiments, the ratio of the average conduit gap-to-outer conduitdiameter about 0.2 or less (e.g., about 0.1 or less, or about 0.05 orless). In further or alternative specific embodiments, the ratio of theinner conduit protrusion length-to-outer conduit diameter is about 0.3or less. In specific embodiments, the ratio of the conduit overlaplength-to-outer conduit diameter is about 10 or more (e.g., about 13 ormore, or about 18 or more) and the ratio of the average conduitgap-to-outer conduit diameter about 0.2 or less (e.g., about 0.1 orless, or about 0.05 or less). In more specific embodiments, the ratio ofthe conduit overlap length-to-outer conduit diameter is about 10 or more(e.g., about 13 or more, or about 18 or more), the ratio of the averageconduit gap-to-outer conduit diameter about 0.2 or less (e.g., about 0.1or less, or about 0.05 or less), and the ratio of the inner conduitprotrusion length-to-outer conduit diameter is about 0.3 or less.

In some embodiments, provided herein is a nozzle (e.g., multi-nozzle)system for producing nanofibers, the system comprising a manifoldcomprising a plurality of supply chambers and at least one (e.g., aplurality of) electrospinning nozzles (e.g., needle apparatuses). Insome embodiments, provided herein is a system comprising a firstmanifold supply chamber, a second manifold supply chamber, a firstconduit (e.g., needle) in fluid contact with the first manifold supplychamber, and a second conduit (e.g., needle) in fluid contact with thesecond supply chamber. In specific embodiments, the first conduit (e.g.,needle) is arranged inside the second conduit (e.g., needle). Inspecific embodiments, the first conduit (e.g., needle) and the secondconduit (e.g., needle) are arranged (e.g., concentrically arranged)about a common axis (e.g., within 5 degrees of the common axis). In someembodiments, the second conduit (e.g., needle) is arranged inside athird conduit (e.g., needle).

Generally, conduits provided herein are enclosed conduits comprising aninlet end and an outlet end and an enclosing wall that surrounds theconduit. Typically, the inlet end is opposite the outlet end. A needleand other “straw-like” structures are examples of enclosed conduitscomprising an inlet end and an outlet end and an enclosing wall thatsurrounds the conduit. Embodiments described herein for “needle”structures are intended to also provide more general disclosure forenclosed conduits.

In some embodiments, a multi-nozzle system described herein comprises amanifold comprising (i) a first manifold inlet in fluid contact with afirst manifold supply chamber, and (ii) a second manifold inlet in fluidcontact with a second manifold supply chamber. In certain embodiments,provided herein is a multi-nozzle system comprising a plurality ofnozzles described herein (e.g., coaxial nozzle (e.g., needle)apparatuses (e.g., wherein the coaxial nozzle apparatus comprises aplurality of coaxially aligned and concentrically arranged conduits)).In specific embodiments, each nozzle component (e.g., coaxial needleapparatus) comprises a first conduit (e.g., needle) comprising a firstsupply end and a first outlet end (e.g., the first supply end being influid contact with the first manifold supply chamber—either directly orvia an intermediary structure). In further or alternative embodiments,each nozzle component (e.g., coaxial needle apparatus) comprises asecond conduit (e.g., needle) comprising a second supply end and asecond outlet end (e.g., the second supply end being in fluid contactwith the second manifold supply manifold—either directly or via anintermediary structure). In specific embodiments, the first conduit(e.g., needle) and second conduit (e.g., needle) are aligned along acommon axis (e.g., within 25% of the diameter of the outer needle andwithin 5 or 10 degrees of the common axis), and the first conduit (e.g.,needle) is positioned inside the second conduit (e.g., needle) for atleast a portion of the length of the first conduit (e.g., needle).

In some embodiments, the manifold further comprises a third inlet influid contact with a third supply chamber. In specific embodiments, eachof the nozzle components (e.g., coaxial needle apparatuses) furthercomprises a third conduit (e.g., needle) comprising a third supply endand a third outlet end. In more specific embodiments, the third supplyend is in fluid contact with the third manifold supply chamber. In someembodiments, the first, second, and third conduits (e.g., needles) arealigned along a common axis, the first conduit (e.g., needle) beingpositioned inside the second conduit (e.g., needle) for at least aportion of the length of the first conduit (e.g., needle), and thesecond conduit (e.g., needle) being positioned inside the third conduit(e.g., needle) for at least a portion of the length of the secondconduit (e.g., needle).

In some embodiments, a system provided herein comprises a stockreservoir (e.g., a syringe) in fluid connection with at least onemanifold inlet (e.g., an inlet in fluid contact with the supply chamberthat is in fluid contact with the inlet of the first or inner conduit(e.g., needle)). In specific embodiments, the system comprises a pump,the pump configured to pump fluid from a stock reservoir through the atleast one manifold inlet and into a manifold supply chamber (e.g., aninlet in fluid contact with the supply chamber that is in fluid contactwith the inlet of the second, third, or outer (e.g., outermost) conduit(e.g., needle)).

In some embodiments, provided herein is a system configured to providecompressed/pressurized gas (e.g., air) to at least one manifold inlet(e.g., that leads to the outer conduit (e.g., needle) of a nozzlecomponent (e.g., needle apparatus)). In certain embodiments, the systemcomprises (a) an air pump connected to a manifold inlet; and/or (b) ahigh-pressure gas (e.g., air) reservoir (e.g., a gas tank) connected toat least one manifold inlet.

In some embodiments, a system provided herein comprises a plurality ofnozzle component (e.g., coaxial needle apparatuses), each nozzlecomponent (e.g., coaxial needle apparatus) comprising at least twoconduits (e.g., at least two needles), with one conduit arranged insidethe other conduit (e.g., wherein the conduits are concentricallyarranged). In certain embodiments, the conduits (e.g., coaxial needles)are suitably aligned with one another. In specific embodiments, theconcentric conduits (e.g., needles of a coaxial needle apparatus)provided herein are aligned within 15 degrees of a common axis. In morespecific embodiments, the concentric conduits (e.g., needles of acoaxial needle apparatus) provided herein are aligned within 10 degreesof a common axis. In still more specific embodiments, the concentricconduits (e.g., needles of a coaxial needle apparatus) provided hereinare aligned within 5 degrees of a common axis. In yet more specificembodiments, the concentric conduits (e.g., needles of a coaxial needleapparatus) provided herein are aligned within 2 degrees of a commonaxis. In preferred embodiments, the concentric conduits (e.g., needlesof a coaxial needle apparatus) provided herein are aligned within 1degrees of a common axis.

In some embodiments, each conduit is arranged around a longitudinalaxis. In certain embodiments, conduits (e.g., needles) of a nozzlecomponent (e.g., coaxial needle) provided herein are aligned around acommon (longitudinal) axis. In specific embodiments, axes of each of theconduits (e.g., needles) of a nozzle component (e.g., coaxial needle)are aligned within 500 microns of one another. In specific embodiments,axes of each of the conduits (e.g., needles) of a nozzle component(e.g., coaxial needle) are aligned within 250 microns of one another. Inspecific embodiments, axes of each of the conduits (e.g., needles) of anozzle component (e.g., coaxial needle) are aligned within 100 micronsof one another. In specific embodiments, axes of each of the conduits(e.g., needles) of a nozzle component (e.g., coaxial needle) are alignedwithin 50 microns of one another. In specific embodiments, axes of eachof the conduits (e.g., needles) of a nozzle component (e.g., coaxialneedle) are aligned within 20 microns of one another.

In some embodiments, the first (or inner) conduit (e.g., needle) has asmaller average diameter and a greater length than the second (or outer)conduit (e.g., needle). In specific embodiments, the first (e.g.,innermost) conduit (e.g., needle) has a smaller average diameter and agreater length than or equal length to the second conduit (e.g.,needle), and the second (e.g., intermediate inner) conduit (e.g.,needle) has a smaller average diameter and a greater length than thethird (e.g., outer or outermost) conduit (e.g., needle). Morespecifically, in some embodiments, the first conduit (e.g., needle) isarranged inside (for at least a portion of its length) inside the secondconduit (e.g., needle), and the second conduit (e.g., needle) isarranged inside (for at least a portion of its length) inside the thirdconduit (e.g., needle) (if present).

In certain embodiments, the third conduit (e.g., needle) has a (inner)diameter of 1.5 mm to 4 mm. In more specific embodiments, the thirdconduit (e.g., needle) has a (inner) diameter of 2 mm to 3 mm (or about9-12 gauge). In still more specific embodiments, the third conduit(e.g., needle) has a (inner) diameter of 2.3 mm to 2.7 mm (or about10-11 gauge).

In some embodiments, the second conduit (e.g., needle) has a (inner)diameter of about 0.8 to about 4 mm (or about 7-18 gauge). In specificembodiments, the second conduit (e.g., needle) has a (inner) diameter of0.8 mm to 2 mm (or about 13-18 gauge), such as when the third conduit(e.g., needle) is present. In specific embodiments, the second conduit(e.g., needle) has a (inner) diameter of 1.3 mm to 1.6 mm (or about14-15 gauge). In some embodiments, the second conduit (e.g., needle) hasan outer diameter (e.g., outer diameter of a wall enclosing the secondconduit, such as the outer wall of a needle) of 1 mm to 2.4 mm (or about13-18 gauge), such as when the third conduit (e.g., needle) is present.In specific embodiments, the second conduit (e.g., needle) has an outerdiameter of 1.8 mm to 2.1 mm (or about 14-15 gauge).

In some embodiments, the first conduit (e.g., needle) has a (inner)diameter of about 0.3 to about 3 mm (or about 9-24 gauge). In specificembodiments, the first conduit (e.g., needle) has a (inner) diameter ofabout 0.5 mm to about 1.2 mm (or about 16-21 gauge). In specificembodiments, the first conduit (e.g., needle) has a (inner) diameter of0.5 mm to 1 mm (or about 17-21 gauge). In specific embodiments, thefirst conduit (e.g., needle) has a (inner) diameter of 0.6 mm to 0.9 mm(or about 18-19 gauge). In some embodiments, the first conduit (e.g.,needle) has an outer diameter (e.g., outer diameter of a wall enclosingthe first conduit, such as the outer wall of a needle) of 0.5 mm to 3.8mm (or about 9-24 gauge). In specific embodiments, the first conduit(e.g., needle) has an outer diameter of about 0.8 mm to about 1.7 mm (orabout 16-21 gauge). In specific embodiments, the first conduit (e.g.,needle) has an outer diameter of 0.8 mm to 1.5 mm (or about 17-21gauge). In more specific embodiments, the first conduit (e.g., needle)has an outer diameter of 1 mm to 1.3 mm (or about 18-19 gauge).

In certain embodiments, nozzle component (e.g., coaxial needleapparatuses) provided herein have a terminal end, with the outlets ofeach of the needles within a nozzle component (e.g., coaxial needleapparatus) configured at the terminal end of the nozzle component (e.g.,coaxial needle apparatus). In certain embodiments, each of the conduits(e.g., needles) of the nozzle component (e.g., coaxial needle apparatus)terminate within 5 mm of one another (e.g., 113 of FIG. 1 or l² of FIG.3 is −5 mm to 5 mm). In specific embodiments, each of the conduits(e.g., needles) of the nozzle component (e.g., coaxial needle apparatus)terminate within 1 mm of one another. In more specific embodiments, eachof the conduits (e.g., needles) of the nozzle apparatus (e.g., coaxialneedle apparatus) terminate within 500 micron of one another. In stillmore specific embodiments, each of the conduits (e.g., needles) of thenozzle apparatus (e.g., coaxial needle apparatus) terminate within 100micron of one another.

In some embodiments, a system provided herein comprises a heater. Inspecific embodiments, the heater is configured to heat one or moresupply manifold, one or more nozzle component (e.g., coaxial needleapparatus), or a combination thereof. In some embodiments, the heater oran additional heater (furnace) is configured to thermally treat the spunnanofibers.

In certain embodiments, a system provided herein comprises a nanofibercollection surface (e.g., a grounded collection surface) in operableproximity to the terminal ends of the nozzle component(s) (e.g., coaxialneedle apparatuses). In some embodiments, the nanofiber collectionsurface is a continuous conveyor collector.

In some embodiments, provided herein is a power supply configured toprovide voltage to the nozzle component (e.g., to provide the electricforce sufficient to electrospin nanofibers from a polymer liquid—e.g.,polymer solution or melt). In some embodiments, the voltage supplied tothe nozzle component is any suitable voltage, such as about 10 kV toabout 50 kV. In more specific embodiments, the voltage supplied is about20 kV to about 30 kV, e.g., about 25 kV.

In specific embodiments, a system provided herein comprises at least onemanifold supply chamber containing therein a liquid polymer composition(i.e., a fluid stock for electrospinning) In specific embodiments, theliquid polymer composition is a composition comprising a polymer and asolvent (e.g., water, dimethylformamide (DMF), a hydrocarbon, or thelike). In certain embodiments, the liquid polymer composition furthercomprises metal precursor (e.g., metal ions (e.g., from disassociatedmetal salt), metal salt, such as metal acetate, metal nitrate, metalhalide, or the like), nanoparticles (e.g., metal, metalloid, metaloxide, ceramic, or the like nanoparticles), or the like. In otherembodiments, the liquid polymer composition comprises a polymer melt(either alone or in combination with another agent). In someembodiments, the liquid polymer has any suitable viscosity, such asabout 10 mPa·s to about 10,000 mPa·s (at 1/s, 20° C.), or about 100mPa·s to about 5000 mPa·s (at 1/s, 20° C.), or about 1500 mPa·s (at 1/s,20° C.). In certain embodiments, liquid polymer is provided to thenozzle at any suitable flow rate. In specific embodiments, the flow rateis about 0.01 to about 0.5 mL/min. In more specific embodiments, theflow rate is about 0.05 to about 0.25 mL/min. In still more specificembodiments, the flow rate is about 0.075 mL/min to about 0.125 mL/min,e.g., about 0.1 mL/min. In some embodiments, at least one manifoldsupply chamber contains therein a fluid consisting essentially of gas(e.g., air). In certain embodiments, the nozzle velocity of the gas isany suitable velocity, e.g., about 0.1 m/s or more. In specificembodiments, the nozzle velocity of the gas is about 1 m/s to about 300m/s. In certain embodiments, the pressure of the gas provided (e.g., tothe manifold inlet or the nozzle) is any suitable pressure, such asabout 2 psi to 20 psi. In specific embodiments, the pressure is about 5psi to about 15 psi. In more specific embodiments, the pressure is about8 to about 12 psi, e.g., about 10 psi.

Also provided herein are processes for electrospinning polymer(including polymer composite and polymer hybrid) nanofibers using anysystem described herein. In certain embodiments, provided herein is aprocess comprising (i) providing into at least one manifold inlet of asystem described herein a liquid polymer composition; and (ii) providinginto at least one other manifold inlet of a system described herein ahigh pressure gas (e.g., air). In some embodiments, also provided hereinare processes for cleaning one or more needle apparatus describedherein, the process comprising providing into at least one manifoldinlet a compressed/high pressure gas (e.g., air). In some instances,this gas removes polymer build-up on the needle apparatus.

In some embodiments, provided herein is a process for producingnanofibers, the process comprising providing a nozzle componentdescribed herein, providing a liquid polymer (e.g., as described herein)to a first (or inner) conduit of said nozzle component, providing apressurized and/or high speed gas to a second (or outer) conduit of saidnozzle component, and providing a voltage to said nozzle component.Suitable nozzle systems include any nozzle system described herein. Infurther embodiments, a collector (e.g., grounded collector) is alsoprovided, whereupon electrospun nanofiber is collected. In certainembodiments, the liquid polymer and gas are provided to the nozzlecomponent via a manifold system described herein.

In certain embodiments, the nozzle component comprises:

-   -   a. a first (or inner) conduit, the first conduit being enclosed        along the length of the conduit by a first wall having an        interior and an exterior surface (e.g., the interior surface        facing the first conduit and at least a portion of the exterior        surface facing the second conduit), the first conduit having a        first inlet (or supply) end and a first outlet end, and the        first conduit having a first diameter defined by the diameter of        the interior surface of the first walls; and    -   b. a second (or outer) conduit, the second conduit being        enclosed along the length of the conduit by a second wall having        an interior surface, the second conduit having a second inlet        (or supply) end and a second outlet end, and the second conduit        having a second diameter defined by the diameter of the interior        surface of the second walls.

In some embodiments, the first and second conduit having a conduitoverlap length. In some embodiments, the first conduit is positionedinside the second conduit, the exterior surface of the first wall andthe interior surface of the second wall being separated by a conduitgap. In some embodiments, the first outlet end protruding beyond thesecond outlet end by a protrusion length. In certain embodiments, thesecond conduit has a second diameter (e.g., diameter of the interiorsurface of the second walls). In certain embodiments, nozzle componentsuseful in such processes include those having any characteristicdescribed herein, such as wherein (i) the ratio of the conduit overlaplength-to-second diameter is about 10 or more (e.g., about 13 or more,or about 18 or more), (ii) the ratio of the average conduitgap-to-second diameter about 0.2 or less (e.g., about 0.1 or less, orabout 0.05 or less), and/or (iii) the ratio of the protrusionlength-to-second diameter is about 0.3 or less.

Any disclosure in this description of a specific value described hereinincludes a disclosure of a value “about” equal to that value (e.g., “1”includes a disclosure of “about 1”). Likewise, any disclosure of anapproximate value in this description also includes disclosure of avalue equal to that value (e.g., “about 1” includes a disclosure of“1”).

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 illustrates a two-needle electrospinning system provided herein.

FIG. 2 illustrates a three-needle electrospinning system providedherein.

FIG. 3 illustrates an alternate configuration of a two-needleelectrospinning system provided herein.

FIG. 4 illustrates a stacked bank electrospinning system providedherein.

FIG. 5 illustrates exemplary polymer nanofibers prepared using a singleneedle apparatus (Panel A) and using needle apparatuses described hereinwith a liquid polymer composition through an inner needle and gasassistance through an outer needle (Panel B).

FIG. 6 illustrates exemplary polymer composite nanofibers prepared usinga single needle apparatus (Panel A) and using needle apparatusesdescribed herein with a liquid polymer composition through an innerneedle and gas assistance through an outer needle (Panel B).

FIG. 7 illustrates a slightly offset coaxial needle apparatus providedherein.

FIG. 8 illustrates exemplary electrospinning nozzle apparatuses providedherein, and cross-sections thereof.

FIG. 9 illustrates an exemplary coaxial needle electrospinning apparatusprovided herein.

DETAILED DESCRIPTION OF THE INVENTION

Provided herein are systems, apparatuses (e.g., nozzle apparatuses andcomponents, such as needle apparatuses), and processes, such as forproducing nanofibers.

In certain embodiments, provided herein are nozzle components (e.g., ofan electrospinning system), such as for the production (e.g., massproduction) of nanofibers. In some embodiments, provided herein is astacked multi-nozzle system for the mass production of nanofibers. Insome instances, the gas-assisted electrospinning (GAES) nozzle systemhas several nozzle components (e.g., coaxial needle apparatuses (e.g.,two-needle apparatuses, three-needle apparatuses, four-needleapparatuses, or the like)), which are configured with a manifold systemin a “stacked” format (e.g., as illustrated in an exemplary embodimentsin FIG. 4).

In some embodiments, a liquid polymer composition (either pure polymermelt, or a combination of polymer and other agents, such as solvents,metal precursors, or the like) is supplied to the inner conduit (e.g.,needle) of the stacked nozzles; and pressurized (e.g., compressed) orhigh velocity gas (e.g., air) is supplied to the outer conduit (e.g.,needle). Also, in some instances, such systems can produce core/shelltype nanofibers using this same configuration, supplying another polymersolution to the outer conduit (e.g., needle) instead of supplying gas.By adding a third conduit (e.g., needle) for compressed air around thesecond conduit, such systems provided herein can produce core/shell typenanofibers with GAES process. Furthermore, we can easily add more piecesfor the various spinning process. In some instances, by supplying air tothe inner conduit (e.g., needle) and liquid polymer to the outer conduit(e.g., needle), hollow fibers can be provided.

Further, if the nozzle components get clogged (e.g., by dried polymer orpolymer/nanoparticles), they can be cleaned by applying compressed airto the polymer supply conduit (e.g., inner conduit (e.g., needle)),which offers a facile self-cleaning mechanism.

Electrospinning is a process for producing fine fibers with diametersranging from micron scale to nano scale through the action of electricalforces. In some instances, the surface tension of polymer melt orsolution is overcome by the electrical force applied to it, a chargedjet is ejected from the surface. In certain instances, the jet initiallyextends in a straight line, then undergoes a whipping motion during theflight from nozzle to collector. In some instances, fibers are collectedon a grounded mesh or plate in the form of a nonwoven web with highsurface area. In general, fiber mats that prepared have a high surfacearea to mass ratio, and thus has great potential for filtration,biomedical, and sensing applications.

However, there is a shortcoming in electrospinning technology, which isa relative low production rate of quality nanofibers. Because of the lowflow rate of polymer melt or solution the production rate is very lowand does not scale profitably to mass production. Systems, apparatuses,and processes described herein overcome such shortcomings. In someinstances, with the help of compressed gas (e.g., air argon, nitrogen,or any other suitable gas), the flow rate of the polymer compositions ismuch (e.g., 10 to 100 times) higher than that of an electrospinningsystem not using compressed gas (e.g., air). In certain embodiments,nanofibers provided using the systems, apparatuses, components, orprocesses described herein have any desired diameter, such as less than2 micron, 50 nm to 1500 nm, 200 nm to 1000 nm, or the like.

FIG. 1 illustrates a non-limiting exemplary system provided herein. Insome instances, the (manifold) system 100 comprises a manifold housing117. In specific instances, the system or manifold 100 comprises (i) afirst manifold inlet 101 in fluid contact with a first manifold supplychamber 102, and (ii) a second manifold inlet 103 in fluid contact witha second manifold supply chamber 104. In some embodiments, the systemcomprises a plurality of nozzle components (e.g., coaxial needleapparatuses) 105. Panel 1B illustrates a nozzle component (e.g., needleapparatus) proved herein separate from the manifold of a systemdescribed herein. In specific instances, nozzle component (e.g., coaxialneedle apparatuses) provided herein each comprise a first conduit (e.g.,needle) 106 comprising a first supply end 107 and a first outlet end108, the first supply end being in fluid contact with the first manifoldsupply chamber 102; and a second conduit (e.g., needle) 109 comprising asecond supply end 110 and a second outlet end 111, the second supply endbeing in fluid contact with the second manifold supply chamber 104. Insome instances, the first conduit supply end is fluidly connected to thefirst supply chamber via a first supply component 119 (as illustrated inFIG. 1, such supply chamber has two components 119 and 119 a). Infurther or alternative embodiments, the second conduit supply end isfluidly connected to the second supply chamber via a second supplycomponent 120. In specific instances, the first conduit (e.g., needle)and second conduit (e.g., needle) are aligned or arranged along oraround a common axis 112. Panel 1C illustrates a cutout 116 of a portionof the nozzle component (e.g., needle apparatus), illustrating a commonaxis along and around which the first and second conduits (e.g.,needles) may be aligned or arranged (the common axis may constitute thecentral longitudinal axis of either or both of the first and secondconduits or needles). 115 illustrates a cross-sectional view of anexemplary bi-conduit nozzle component (e.g., two-needle coaxial needleapparatus). Generally, the first conduit (e.g., needle) 106 ispositioned inside the second conduit (e.g., needle) 109 for at least aportion of the length of the first conduit (e.g., needle) 118 (1′). Insome embodiments, the first conduit comprises a first wall 121 (e.g.,that encloses the conduit longitudinally) and the second conduitcomprises a second wall 122 (e.g., that encloses the conduitlongitudinally). In certain instances, the first conduit (e.g., needle)protrudes 106 b a certain distance 113 (l²) beyond the second conduitoutlet. In some instances, a voltage is supplied to the needle component105 (e.g., voltage sufficient to overcome the surface tension of aliquid polymer composition—such as 5 kV to 100 kV, e.g., 8 kV to 40 kV,or 20 kV to 30 kV) to produce a jet 114, which is collected on acollection surface (not shown) as a nanofiber. In some instances, apolymer composition (fluid stock) is optionally provided to one or moremanifold inlet by any suitable device, e.g., by a syringe or a pumpSimilarly, a (pressurized/compressed) gas is optionally provided to oneor more manifold inlet by any suitable device, e.g., a gas canister,pump, or the like.

FIG. 2 illustrates another non-limiting exemplary system providedherein. In some instances, the system comprises a manifold. In specificinstances, the system or manifold comprises (i) a first manifold inletin fluid contact with a first manifold supply chamber 201, (ii) a secondmanifold inlet in fluid contact with a second manifold supply chamber202, and (iii) a third manifold inlet in fluid contact with a thirdmanifold supply chamber 203. In specific embodiments, the system isconfigured to receive a fluid polymer composition into any manifoldsupply chamber (e.g., as shown in FIG. 2—in the first manifold supplychamber 201 and the second manifold supply chamber 202) via any suitabledevice, such as a pump (not shown) or syringe 205. In further specificembodiments, the system is configured to receive a gas into any manifoldsupply chamber (e.g., as shown in FIG. 2—in the third manifold supplychamber 203) via any suitable device 206 (e.g., via gas tank or pump).In some embodiments, the system comprises a plurality of nozzlecomponents (e.g., coaxial needle apparatuses) 204. In specificinstances, nozzle components (e.g., coaxial needle apparatuses) providedherein each comprise a first conduit (e.g., needle) comprising a firstsupply end and a first outlet end, the first supply end being in fluidcontact with the first manifold supply chamber; a second conduit (e.g.,needle) comprising a second supply end and a second outlet end, thesecond supply end being in fluid contact with the second manifold supplychamber; and a third conduit (e.g., needle) comprising a third supplyend and a third outlet end, the third supply end being in fluid contactwith the third manifold supply chamber. In specific instances, the firstconduit (e.g., needle) and second conduit (e.g., needle) are alignedalong a common axis 112. 207 illustrates a cross-sectional view of anexemplary tri-conduit nozzle component (e.g., three-needle coaxialneedle apparatus), with the third conduit (e.g., needle) 208 surroundingthe second conduit (e.g., needle) 209, which in turn surrounds the firstconduit (e.g., needle) 210. Generally, the first conduit (e.g., needle)210 is positioned inside the second conduit (e.g., needle) 209 for atleast a portion of the length of the first conduit (e.g., needle), andthe second conduit (e.g., needle) 209 is positioned inside the thirdconduit (e.g., needle) 208 for at least a portion of the length of thesecond conduit (e.g., needle). In some instances, a voltage is supplied211 to the nozzle component (e.g., needle apparatus) 204 (e.g., voltagesufficient to overcome the surface tension of a liquid polymer orpolymer solution) to produce a jet, which is collected on a collectionsurface 212 as a nanofiber. Systems described herein optionally comprisea single manifold housing that contains the first, second, and anyadditional supply chambers (e.g., as illustrated in FIG. 1 and FIG. 2).In other embodiments, systems described herein comprise separatemanifold systems, e.g., wherein a system comprises a first manifoldhousing a first supply chamber, with a first manifold inlet in fluidcontact with a first manifold supply chamber and a second manifoldhousing a second supply chamber, with a second manifold inlet in fluidcontact with a second manifold supply chamber.

FIG. 3 illustrates a section of a non-limiting exemplary system providedherein. In some instances, the system comprises a manifold 100. Inspecific instances, the manifold 100 comprises (i) a first manifoldsupply chamber 102, and (ii) a second manifold supply chamber 104. Insome embodiments, the system comprises a plurality of multi-conduitnozzle components (e.g., coaxial needle apparatuses) 105. In specificinstances, multi-conduit nozzle components (e.g., coaxial needleapparatuses) provided herein each comprise a first conduit (e.g.,needle) 106 comprising a first supply end and a first outlet end 108,the first supply end being in fluid contact with the first manifoldsupply chamber 102; and a second conduit (e.g., needle) 109 comprising asecond supply end and a second outlet end 111, the second supply endbeing in fluid contact with the second manifold supply chamber 104. Forillustrative purposes, a portion of the second conduit is removed 312 toprovide display of the first conduit position inside the second conduit.Generally, the first conduit is positioned inside the second conduit.Typically, the first and second conduits are enclosed, with theexception of the supply and outlet ends. In specific instances, thefirst conduit (e.g., needle) and second conduit (e.g., needle) arealigned along a common axis 112, such as illustrated in FIG. 3 (or,e.g., wherein the axes of the conduits is within 0.5 mm, 0.25 mm, 0.1 mmor the like of one another). In some instances, the system is configuredto allow a voltage to be supplied to the needle apparatus 105 (e.g.,voltage sufficient to overcome the surface tension of a liquid polymeror polymer solution) to produce a jet, which is collected on acollection surface (not shown) as a nanofiber.

In some embodiments, the first conduit (e.g., needle) has any suitablediameter 309 (e.g., inner wall diameter (d¹) and/or outer wall diameter(d″)), such as a diameter described herein. In certain embodiments, thesecond conduit (e.g., needle) has any suitable diameter 310 (e.g., innerdiameter (d²)), such as a diameter described herein.

In certain embodiments, provided herein is a nozzle apparatus comprisinga first conduit and a second conduit, the first conduit arranged insidethe second conduit. In some embodiments, the nozzle apparatus comprises(i) a nozzle component comprising the first conduit and the secondconduit, and (ii) an optional supply component (e.g., that is operablyand fluidly connected to the nozzle component and a supply source, suchas a manifold system described herein). In some embodiments, a nozzleapparatus provided herein comprises (i) a first conduit (e.g., needle)106 comprising a portion that has substantially parallel (e.g.,parallel, or within 15 degrees, within 10 degrees, or within 5 degreesof parallel) walls 303 and (ii) an optional first supply component 307that has non-parallel walls 308 (e.g., substantially non-parallel walls,or greater than 15 degrees, greater than 10 degrees, or greater than 5degree from parallel). Similarly, in certain embodiments, the nozzleapparatus comprises (i) a second conduit (e.g., needle) comprising aportion that has substantially parallel walls 302 (e.g., parallel—asshown, or within 15 degrees, within 10 degrees, or within 5 degrees ofparallel), and (ii) an optional second supply component 304 that hasnon-parallel walls 301 (e.g., substantially non-parallel walls, orgreater than 15 degrees, greater than 10 degrees, or greater than 5degree from parallel—e.g., as illustrated by the angle 305). In someembodiments, the walls of the outer conduit of the nozzle component(e.g., needle, such as the second needle 109 as illustrated in FIG. 3)of the nozzle apparatus are aligned (e.g., parallel—as shown, or within15 degrees, within 10 degrees, or within 5 degrees of parallel) (e.g.,and are aligned (e.g., parallel—as shown, or within 15 degrees, within10 degrees, or within 5 degrees of parallel) with the walls of the innerconduit(s) (e.g., needle(s), such as the first needle 106)) for at leasta portion of the length of the nozzle (e.g., needle) 306 (l¹) apparatus.In certain embodiments, the length of l¹ is long enough to provide highperformance and/or highly uniform nanofibers. In some embodiments, thelength of l¹ is long enough to provide a system suitable for highthroughput production of nanofibers. In some embodiments, the first orinner conduit extends beyond (or protrudes beyond) the end of the secondor outer conduit 311 (l²). In certain instances, the outer surface ofthe wall enclosing the first (inner) conduit and the inner surface ofthe wall enclosing the second (outer) conduit are set off by a certaindistance 313. In some embodiments, the average of this distance is theconduit gap (d⁴).

In specific embodiments, the ratio of the length l¹ to the diameter ofthe inner conduit (e.g., outer diameter of the inner conduit, such as aneedle) (e.g., the first needle 106 in FIG. 3 having a diameter d¹) isat least 20. In more specific embodiments, ratio is at least 25, atleast 30, at least 40, at least 50, or the like. In further oradditional specific embodiments, the ratio of l¹ to the diameter of theouter conduit (e.g., needle) (e.g., the second conduit 109 in FIG. 3having a diameter d²) is at least 10, at least 20, at least 25, at least30, at least 40, at least 50, or the like.

FIG. 8 illustrates exemplary electrospinning nozzle apparatuses 800 and830 provided herein. Illustrated by both nozzle components 800 and 830some embodiments, the nozzle apparatus comprises a nozzle componentcomprising a first conduit, the first conduit being enclosed along thelength of the conduit by a first wall 801 and 831 having an interior andan exterior surface, and the first conduit having a first inlet (orsupply) end 802 and 832 (e.g., fluidly connected to a first supplychamber and configured to receive a liquid polymer—such as a liquidpolymer composition) and a first outlet end 803 and 833. Generally, thefirst conduit has a first diameter 804 and 834 (e.g., the averagediameter as measured to the inner surface of the wall enclosing theconduit (d′) or the average diameter as measured to the outer surface ofthe wall enclosing the conduit (d″)). In further instances, the nozzlecomponent comprising a second conduit, the second conduit being enclosedalong the length of the conduit by a second wall 805 and 835 having aninterior and an exterior surface, and the second conduit having a secondinlet (or supply) end 806 and 836 (e.g., fluidly connected to a secondsupply chamber and configured to receive a gas—such as a high velocityor pressurized gas (e.g., air)) and a second outlet end 807 and 837. Insome instances, the second inlet (supply) end 806 and 836 are connectedto a supply chamber (e.g., in a manifold described herein—e.g.,comprising the second supply chamber and, optionally, the first supplychamber). In certain instances, the second inlet (supply) end 806 and836 are connected to the second supply chamber via a supply component.FIG. 8 illustrates an exemplary supply component comprising a connectionsupply component (e.g., tube) 813 and 843 that fluidly connects 814 and844 the supply chamber (not shown) to an inlet supply component 815 and845, which is fluidly connected to the inlet end of the conduit. Thefigure illustrates such a configuration for the outer conduit, but sucha configuration is also contemplated for the inner and any intermediateconduits as well. Generally, the first conduit has a first diameter 808and 838 (e.g., the average diameter as measured to the inner surface ofthe wall enclosing the conduit (d²)). The first and second conduits haveany suitable shape. In some embodiments, the conduits are cylindrical(e.g., circular or elliptical), prismatic (e.g., a octagonal prism),conical (e.g., a truncated cone—e.g., as illustrated by the outerconduit 835) (e.g., circular or elliptical), pyramidal (e.g., atruncated pyramid, such as a truncated octagonal pyramid), or the like.In specific embodiments, the conduits are cylindrical (e.g., wherein theconduits and walls enclosing said conduits form needles). In someinstances, the walls of a conduit are parallel, or within about 1 or 2degrees of parallel (e.g., wherein the conduit forms a cylinder orprism). For example, the nozzle apparatus 800 comprise a first andsecond conduit having parallel walls 801 and 805 (e.g., parallel to thewall on the opposite side of the conduit, e.g., as illustrated by 801a/801 b and 805 a/805 b, or to a central longitudinal axis 809). Inother embodiments, the walls of a conduit are not parallel (e.g.,wherein the diameter is wider at the inlet end than the outlet end, suchas when the conduit forms a cone (e.g., truncated cone) or pyramid(e.g., truncated pyramid)). For example, the nozzle apparatus 830comprise a first conduit having parallel walls 831 (e.g., parallel tothe wall on the opposite side of the conduit, e.g., as illustrated by831 a/831 b, or to a central longitudinal axis 839) and a second conduithaving non-parallel walls 835 (e.g., not parallel or angled to the wallon the opposite side of the conduit, e.g., as illustrated by 835 a/835b, or to a central longitudinal axis 839). In certain embodiments, thewalls of a conduit are within about 15 degrees of parallel (e.g., asmeasured against the central longitudinal axis, or half of the anglebetween opposite sides of the wall), or within about 10 degrees ofparallel. In specific embodiments, the walls of a conduit are withinabout 5 degrees of parallel (e.g., within about 3 degrees or 2 degreesof parallel). In some instances, conical or pyramidal conduits areutilized. In such embodiments, the diameters for conduits not havingparallel walls refer to the average width or diameter of said conduit.In certain embodiments, the angle of the cone or pyramid is about 15degrees or less (e.g., the average angle of the conduit sides/walls asmeasured against a central longitudinal axis or against the conduitside/wall opposite), or about 10 degrees or less. In specificembodiments, the angle of the cone or pyramid is about 5 degrees or less(e.g., about 3 degrees or less). Generally, the first conduit 801 and831 and second conduit 805 and 835 having a conduit overlap length 810and 840 (l′), wherein the first conduit is positioned inside the secondconduit (for at least a portion of the length of the first and/or secondconduit). In some instances, the exterior surface of the first wall andthe interior surface of the second wall are separated by a conduit gap811 and 841 (d⁴). In certain instances, the first outlet end protrudesbeyond the second outlet end by a protrusion length 812 and 842 (l²). Incertain instances, the ratio of the conduit overlap length-to-seconddiameter is any suitable amount, such as an amount described herein,e.g., about 10 or more (e.g., about 13 or more, or about 18 or more). Infurther or alternative instances, the ratio of the average conduitgap-to-second diameter is any suitable amount, such as an amountdescribed herein, e.g., about 0.2 or less (e.g., about 0.1 or less, orabout 0.05 or less). In further or alternative instances, the ratio ofthe protrusion length-to-second diameter is any suitable amount, such asan amount described herein, e.g., about 0.3 or less.

FIG. 8 also illustrates cross-sections of various nozzle componentsprovided herein 850, 860 and 870. Each comprises a first conduit 851,861 and 871 and second conduit 854, 864, and 874. As discussed herein,in some instances, the first conduit is enclosed along the length of theconduit by a first wall 852, 862 and 872 having an interior and anexterior surface and the second conduit is enclosed along the length ofthe conduit by a second wall 855, 865 and 875 having an interior and anexterior surface. Generally, the first conduit has any suitable firstdiameter 853, 863 and 864 (d′) and any suitable second diameter 856,866, and 876 (d²). The cross-dimensional shape of the conduit is anysuitable shape, and is optionally different at different points alongthe conduit. In some instances, the cross-sectional shape of the conduitis circular 851/854 and 871/874, elliptical, polygonal 861/864, or thelike.

In some instances, coaxially configured nozzles provided herein andcoaxial gas assisted electrospinning provided herein comprises providinga first conduit or fluid stock along a first longitudinal axis, andproviding a second conduit or gas (e.g., pressurized or high velocitygas) around a second longitudinal axis (e.g., and electrospinning thefluid stock in a process thereof). In specific embodiments, the firstand second longitudinal axes are the same. In other embodiments, thefirst and second longitudinal axes are different. In certainembodiments, the first and second longitudinal axes are within 500microns, within 100 microns, within 50 microns, or the like of eachother. In some embodiments, the first and second longitudinal axes arealigned within 15 degrees, within 10 degrees, within 5 degrees, within 3degrees, within 1 degree, or the like of each other. For example, FIG. 8illustrates a cross section of a nozzle component 870 having an innerconduit 871 that is off-center (or does not share a central longitudinalaxis) with an outer conduit 874. In some instances, the conduit gap(e.g., measurement between the outer surface of the inner wall and innersurface of the outer wall) is optionally averaged—e.g., determined byhalving the difference between the diameter of the inner surface of theouter wall 876 and the diameter of the outer surface of the inner wall872. In some instances, the smallest distance between the inner surfaceof the outer wall 876 and the diameter of the outer surface of the innerwall 872 is at least 10% (e.g., at least 25%, at least 50%, or anysuitable percentage) of the largest distance between the inner surfaceof the outer wall 876 and the diameter of the outer surface of the innerwall 872.

For further illustration, FIG. 9 provides a non-limiting threedimensional illustration (with illustrative cut outs 901 and 902) of anozzle component (e.g., coaxial needle nozzle component) 900 providedherein. In specific instances, the needle apparatus (or nozzlecomponent) comprises a first (inner) needle 904 comprising a first(inner) conduit 904 enclosed by a first wall 905, the first wallcomprising a first wall inner surface 906, a first wall outer surface907, a first (inner) outlet end 908, a first (inner) inlet (supply) end(e.g., configured to be in fluid contact with a first supply chamber,and/or to receive a liquid polymer), a first inner diameter 918 (d′) anda first outer diameter 919 (d″). In further instances, the needleapparatus (or nozzle component) comprises a second (outer) needle 909comprising a second (outer) conduit 910 enclosed by a second wall 911,the first wall comprising a second wall inner surface 912, a (optional)second wall outer surface 913, a second (outer) outlet end 914, a second(outer) inlet (supply) end (e.g., configured to be in fluid contact witha second supply chamber, and/or to receive a liquid polymer or highvelocity or high pressure gas (e.g., air)) a second inner diameter 920(d²) and (optionally) a second outer diameter.

Generally, the first (inner) needle 903 is positioned inside the secondneedle 909 for at least a portion of the length of the first needle 915(l′). In certain instances, the first needle 903 (outlet end 908)protrudes a certain distance 916 (l²) beyond the second needle 909(outlet end 914). As discussed for other embodiments described herein,in some instances, the exterior surface of the first (inner) wall 907and the interior surface of the second (outer) wall 912 are separated bya conduit gap 917 (d⁴). In certain instances, the ratio of the conduitoverlap length 915-to-second inner diameter 920 is any suitable amount,such as an amount described herein, e.g., about 10 or more (e.g., about13 or more, or about 18 or more). In further or alternative instances,the ratio of the average conduit gap 917-to-second inner diameter 920 isany suitable amount, such as an amount described herein, e.g., about 0.2or less (e.g., about 0.1 or less, or about 0.05 or less). In further oralternative instances, the ratio of the protrusion length 916-to-secondinner diameter 920 is any suitable amount, such as an amount describedherein, e.g., about 0.3 or less.

In some embodiments, a system provided herein comprises an apparatuscomprising a plurality of rows of nozzle components (e.g., coaxialneedle apparatuses) (nozzles in the rows and columns may be aligned oroffset—both are aligned in the examples illustrated in FIG. 4). FIG. 4illustrates two examples of such systems. In some instances, a (e.g.,single) first manifold supply chamber (e.g., having a single inlet101—e.g., as illustrated in the upper panel of FIG. 4) optionally feedsthe first conduits (e.g., needles) of each row of nozzles (e.g., needleapparatuses). In certain instances, a (e.g., single) second manifoldsupply chamber (e.g., having a single inlet 103—e.g., as illustrated inthe upper panel of FIG. 4) optionally feeds the second conduits (e.g.,needles) of each row of nozzles (e.g., needle apparatuses). In someinstances, e.g., wherein multiple rows and of nozzles (e.g., needleapparatuses) are utilized, a plurality of first manifold supplychambers, a plurality of second manifold supply chambers, or the likeare optionally utilized. In addition, in some instances, multiple firstinlets 101 may feed the first manifold supply chamber(s), and/ormultiple second inlets 103 may feed the second manifold supplychamber(s) (e.g., as illustrated in the lower panel of FIG. 4).

In certain embodiments, conduits (e.g., needles) of a nozzle component(e.g., coaxial needle apparatus) provided herein are aligned around acommon (longitudinal) axis. In some embodiments, the (longitudinal) axesof the conduits (e.g., needles) of a nozzle component (e.g., coaxialneedle apparatus) provided herein are slightly offset. In specificinstances, such offset is small enough that high performance andthroughput characteristics of the system are retained. FIG. 7illustrates that the central logitindual axis of an inner conduit (e.g.,needle) 702 may be slightly offset from the central longitudinal axis ofan outer conduit (e.g., needle) 701, such as by an amount 703 (d³). Inspecific embodiments, axes of each of the conduits (e.g., needles) of anozzle component (e.g., coaxial needle) are aligned within any suitabledistance, e.g., within about 0.5 mm, within about 200 microns, or within100 microns of one another (e.g., 100 microns>d³). In specificembodiments, axes of each of the conduits (e.g., needles) of a nozzlecomponent (e.g., coaxial needle) are aligned within 50 microns of oneanother. In specific embodiments, axes of each of the conduits (e.g.,needles) of a nozzle component (e.g., coaxial needle) are aligned within20 microns of one another. In some embodiments, the offset is less than0.1 of the diameter of the inner conduit (e.g., needle) (e.g.,d³/d^(i)<0.1). In some embodiments, the offset is less than 0.05, lessthan 0.03, or less than 0.01 of the diameter of the inner conduit (e.g.,needle).

Any suitable polymer is optionally utilized in systems, apparatuses, orprocessed described herein e.g., any electrospinnable polymer (e.g.,electrospinnable as a melt or in solution). Exemplary polymers suitablefor use in systems, apparatuses, or processed described herein includebut are not limited to polyvinyl alcohol (“PVA”), polyvinyl acetate(“PVAc”), polyethylene oxide (“PEO”), polyvinyl ether, polyvinylpyrrolidone, polyglycolic acid, polyvinylidene difluoride (PVDF),hydroxyethylcellulose (“HEC”), ethylcellulose, cellulose ethers,polyacrylic acid, polyisocyanate, and the like. In some embodiments, thepolymer is isolated from biological material. In some embodiments, thepolymer is starch, chitosan, xanthan, agar, guar gum, and the like. Inother instances, other polymers, such as polyacrylonitrile (“PAN”) areoptionally utilized (e.g., with DMF as a solvent). In other instances, apolyacrylate (e.g., polyalkacrylate, polyacrylic acid,polyalkylalkacrylate, or the like) is optionally utilized.

Any suitable polymer concentrations may be utilized in the systems,apparatuses, components, or processes described herein. In someinstances, a liquid polymer (e.g., polymer composition) provided hereinis neat polymer (meaning about 100% polymer). In other instances, apolymer composition comprises solvent and/or an additional component(such as metal precursor, metal ion, nanoparticle, or the like). In someinstances, the polymer concentration in a polymer composition providedherein is, e.g., 550 wt. %. In specific embodiments, the polymerconcentration is below 20 wt %. In more specific embodiments, thepolymer concentration is 2-20 wt %. In still more specific embodiments,the polymer concentration is 8-12 wt %. Specific polymers, metalprecursors, nanoparticles, and process parameters set forth in U.S.Patent Application Publication No. 2011/0148005, U.S. Patent ApplicationPublication No. 2007/0259655, U.S. Pat. No. 7,083,854, InternationalPatent Application Publication No. WO 2011/100743, International PatentApplication Publication No. WO 2013/0033367, and International PatentApplication No. PCT/US13/28132 are contemplated herein, e.g., for usewith the system described herein, and all of which are incorporatedherein for such disclosure.

In some embodiments, compressed gas is provided to a system here at anysuitable pressure. In specific instances, the gas pressure is about 0.1to 10 kgf/cm². In more specific embodiments, the gas is provided at apressure of about 0.5-3 kgf/cm².

Any suitable distance may be utilized between the nozzle and collectionplate. In some instances, the distance is about 3-100 cm. In morespecific instances, the distance is about 5-50 cm, or more specificallyabout 10-25 cm.

In some embodiments, the flow rate of the fluid stock (e.g., to eachneedle apparatus) is about 0.05 mL/min to 3 mL/min, or more specificallyabout 0.1-0.5.ml/min.

In various embodiments, the supply components, manifold components, andnozzle components comprise any suitable material. In some embodiments,such materials are resistant to corrosion, such as plastics (e.g.,polyethylene, polypropylene, etc.) or inert or semi-inert metals. Insome embodiments, nozzle components (e.g., the conduit walls) providedherein comprise stainless steel, brass, bronze, or the like. In someembodiments, nozzle components (e.g., the conduit walls) provided hereincomprise plastic (e.g., polyethylene), stainless steel, brass, bronze,or the like.

In some embodiments, the multi-nozzle system allows for high throughputnanofiber processing. In certain embodiments, the multi-nozzle systemalso provides for the preparation of high performance nanofibers—e.g.,nanofibers having uniform structures and components. In certainembodiments, such nanofibers allow for the production of nanofibers thathave narrow, uniform diameters. For example, in some instances, thestandard deviation of nanofibers provided, or prepared according tosystems and processes described, herein is less than 100% of the averagediameter, less than 50% of the average diameter, less than 25% of theaverage diameter, or the like.

EXAMPLES Example 1—Polymer Nanofibers

Polyvinyl alcohol (PVA) (M_(w) 78,000) is charged in DI water withconcentration of 8-12 wt %. The prepared polymer composition is pumpedinto the inner channel of spinneret and compressed air gas is providedthrough the outer channel with the pressure of 0.5-3 kgf/cm². Thedistance between the nozzle and collection plate is kept to 10-25 cm,and the flow rate of 0.1-0.5.ml/min is maintained. A charge of +20 to+30 kV is maintained at the needle. FIG. 5 (Panel A) illustrates an SEMof PVA nanofibers prepared without gas assistance, and (Panel B)illustrates an SEM of PVA nanofibers prepared with gas assistance.Nanofibers prepared with gas assistance showed significantly fewer beadstructures in the nanofibers, as well as much higher production rates.

Example 2—Polymer Composite/Hybrid Nanofibers

Polyvinyl alcohol (PVA) (M_(w) 78,000) is provided and nanoparticleswith the size of 20-30 nm are supplied. PVA is dissolved in DI waterwith concentration of 8-12 wt %. And nanoparticles are added in the PVAsolution to prepare PVA/NP composition. The weight ratio of PVA tonanoparticles is 0.5-5, and to prevent the aggregation of nanoparticlesthe composition is sonicated for 3-5 hrs.

The prepared polymer composition is pumped into the inner channel ofspinneret and compressed air gas is provided through the outer channelwith the pressure of 0.5-3 kgf/cm². The distance between the nozzle andcollection plate is kept to 10-25 cm, and the flow rate of0.1-0.5.ml/min is maintained. A charge of +20 to +30 kV is maintained atthe needle. FIG. 6 (Panel A) illustrates an SEM of PVA nanofibersprepared without gas assistance, and (Panel B) illustrates an SEM of PVAnanofibers prepared with gas assistance.

Example 3—Nozzle Configuration

Polyvinyl alcohol (PVA) is provided and metal precursor are supplied.PVA is dissolved in DI water with concentration of 8-12 wt %. And metalprecursor is added in the PVA solution to prepare PVA/precursor aqueouscomposition. The weight ratio of PVA to precursor is about 2:3.

The prepared polymer composition is pumped into the inner channel of thenozzle at a flow rate of about 0.1 mL/min (e.g., about 0.075 to about0.12 mL/min) and compressed air gas is provided through the outerchannel with the pressure of about 10 psi (e.g., about 8 psi to about 12psi). The distance between the nozzle and collection plate is kept to20-30 cm (e.g., about 25 cm). A charge of +20 to +30 kV (e.g., about +25kV) is maintained at the needle.

A manifold system comprising a plurality of nozzles described wasutilized to prepare polymer composite nanofibers. Various nozzleconfigurations were utilized, such as set forth in Table 1. The term dl′refers to the diameter (in mm) of the outer walls of the first (inner)conduit; d2 refers to the diameter (in mm) of the second (outer)conduit; d4 refers to the conduit gap (in mm) (the average distancebetween the outer surface of the wall enclosing the first (inner)conduit and the inner surface of the wall enclosing the second (outer)conduit); l1 refers to the conduit overlap length (in mm) (the lengthover which the first conduit runs within the second conduit); and l2refers to the protrusion length (in mm) of the first inner conduit(e.g., the distance that the first (inner conduit) outlet extends beyondthe second (outer conduit) outlet). The spinnability is measuredqualitatively, with 1 being extremely poor electrospinnability(nanofiber formation) and 5 being extremely good electrospinnability.

TABLE 1 Nozzle Parameters dl′ d2 d4 11 12 d4/d2 11/d2 12/d2 Spinnability1 0.90 1.4 0.24 30 0.27 0.17 22 0.20 4 2 1.27 1.6 0.17 5 0.77 0.10 3.10.48 1 3 1.27 1.6 0.17 5 0.32 0.10 3.1 0.20 2 4 1.27 1.6 0.17 15 0.370.10 9.4 0.23 2 5 1.27 1.6 0.17 30 0.4 0.10 18.8 0.25 4 6 1.47 1.6 0.0630 0.48 0.04 18.8 0.30 4 7 1.47 1.6 0.06 30 0.61 0.04 18.8 0.38 4 8 1.471.6 0.06 30 0.44 0.04 18.8 0.28 5 9 1.47 1.6 0.06 30 1.2 0.04 18.8 0.751 10 1.47 1.8 0.165 30 0.4 0.09 16.6 0.22 3 11 1.65 2.2 0.25 30 0.330.12 13.9 0.15 4

Table 1 illustrates that superior electrospinnability is achieved atlower values of d4/d2 (e.g., compare 5 and 8), at higher values of l1/d2(e.g., compare 2 and 3, 4 and 5), and at lower values of l2/d2 (e.g.,compare 8 and 9).

What is claimed is:
 1. A system comprising a plurality of nozzles, andone or more power source: the one or more power source being configuredto provide a voltage to each of the plurality of nozzles; and each ofthe plurality of nozzles comprising: a first conduit, the first conduitbeing enclosed along the length of the conduit by a first wall having aninterior surface and an exterior surface, the first conduit having afirst inlet end and a first outlet end, the first inlet end being influid contact with a reservoir via a first supply component, and thefirst conduit having a first diameter; and a second conduit, the secondconduit being enclosed along the length of the conduit by a second wallhaving an interior surface, the second conduit having a diameter (d²),the second conduit having a second inlet end and a second outlet end,and the second inlet end being in fluid contact with a gas pump or apressurized canister via a second supply component, the exterior surfaceof the first wall and the interior surface of the second wall beingseparated by a conduit gap (d⁴), the first and second conduit having aconduit overlap length, wherein the first conduit is positioned insidethe second conduit (l¹), wherein the first supply component comprises awall non-parallel to the first conduit with an angle of greater than 5degree from parallel; and/or the second supply component comprises awall non-parallel to the second conduit with an angle of greater than 5degree from parallel.
 2. The system of claim 1, wherein d⁴/d² is 0.2 orless.
 3. The system of claim 1, wherein the first and second conduithaving a conduit overlap length, wherein the first conduit is positionedinside the second conduit (l¹), and wherein l¹/d² is about 13 or more.4. The system of claim 3, wherein l¹/d² is about 15 or more.
 5. Thesystem of claim 1, wherein the first outlet end protruding beyond thesecond outlet end by a protrusion length (l²), wherein l²/d² is about0.5 or less.
 6. A system comprising a plurality of nozzles, and one ormore power source: the one or more power source being configured toprovide a voltage to each of the plurality of nozzles; and each of theplurality of nozzles comprising: a first conduit, the first conduitbeing enclosed along the length of the conduit by a first wall having aninterior surface and an exterior surface, the first conduit having afirst inlet end and a first outlet end, the first inlet end being influid contact with a reservoir via a first supply component, and thefirst conduit having a first diameter; and a second conduit, the secondconduit being enclosed along the length of the conduit by a second wallhaving an interior surface, the second conduit having a diameter (d²),the second conduit having a second inlet end and a second outlet end,and the second inlet end being in fluid contact with a gas tank, a gaspump or a pressurized canister via a second supply component, theexterior surface of the first wall and the interior surface of thesecond wall being separated by a conduit gap (d⁴), wherein d⁴/d² is 0.2or less; the first and second conduit having a conduit overlap length,wherein the first conduit is positioned inside the second conduit (l¹),wherein l¹/d² is about 10 or more; and the first outlet end protrudingbeyond the second outlet end, and the first outlet end protruding beyondthe second outlet end by a protrusion length (l²), wherein l²/d² isabout 0.5 or less.
 7. A system comprising one or more nozzle, one ormore power source, and at least two supply chambers: the one or morepower source being configured to provide a voltage to each of theplurality of nozzles; and each of the one or more nozzles comprising: afirst conduit, the first conduit being enclosed along the length of theconduit by a first wall having an interior surface and an exteriorsurface, the first conduit having a first supply end and a first outletend, the first supply end is fluidly connected to a first supply chamberof the at least two supply chamber via a first supply component, thefirst conduit having a diameter (d¹); and a second conduit, the secondconduit being enclosed along the length of the conduit by a second wallhaving an interior surface, the second conduit having a second supplyend and a second outlet end, the second supply end is fluidly connectedto a second supply chamber of the at least two supply chamber via asecond supply component, the second conduit having a diameter (d²);wherein the first conduit is positioned inside the second conduit suchthat the first conduit and the second conduit having a conduit overlaplength (l¹).
 8. The system of claim 7, wherein the first conduit and thesecond conduit are concentrically arranged within 10 degrees of a commonaxis.
 9. The system of claim 7, wherein the first supply component andthe second supply component are substantially concentrically arranged.10. The system of claim 7, wherein at least a portion of the firstsupply component has a diameter larger than the diameter of the firstconduit d¹, and at least a portion of the second supply component has adiameter larger than the diameter of the second conduit d².
 11. Thesystem of claim 7, wherein the first supply component is positionedinside the second supply component with at least a portion overlappedalong a common axis.
 12. The system of claim 7, wherein the secondsupply component is positioned under the first supply component with orwithout overlap.
 13. The system of claim 7, wherein the first conduithas substantially parallel walls and the first supply component hassubstantially non-parallel walls, and/or wherein the second conduit hassubstantially parallel walls and the second supply component hassubstantially non-parallel walls.
 14. The system of claim 7, wherein thefirst supply component comprises a wall non-parallel to the firstconduit with an angle of greater than 5 degree from parallel; and/or thesecond supply component comprises a wall non-parallel to the secondconduit with an angle of greater than 5 degree from parallel.
 15. Thesystem of claim 7, wherein the first supply chamber supplies a liquidpolymer composition and wherein the second supply chamber suppliespressurized gas.
 16. The system of claim 7, wherein each of the one ormore nozzles further comprises a third conduit comprising a third supplyend and a third outlet end, and the third supply end is fluidlyconnected to a third supply chamber via a third supply component. 17.The system of claim 16, wherein the first, second, and third conduitsare aligned substantially along a common axis with at least a portionoverlapped and wherein the first, second and third supply components arealigned substantially along the common axis without overlap among thefirst, second and third supply components.
 18. The system of claim 7,wherein the first conduit protrudes beyond the end of the second conduitby a protrusion length of 0 mm to about 5 mm.
 19. The system of claim 7,further comprising a housing that contains at least two supply chambersincluding the first supply chamber, the second supply chamber andoptionally a third supply chamber.
 20. The system of claim 7, wherein across-dimensional shape of the first and/or the second conduit iscircular, elliptical or polygonal, and optionally different at differentpoints along the first and/or the second conduit.